1. Field of the Invention
The present invention relates to the fabrication of optical devices for fiber optic communication systems, and, in particular, to a method for reducing plating sliver contamination caused by friction processes during fabrication of such optical devices.
2. Description of the Related Art
In fiber optic communication systems, it is often desirable to block a particular wavelength of light or to have a particular wavelength of light pass through a fiber optic cable. The blocking or passing through of particular wavelengths of light is accomplished using optical devices known as isolators and filters, respectively.
FIG. 1 shows a side view of a conventional optical device 100 that will function as either an isolator or a filter, depending on the selection of device components. Optical device 100 comprises a device body 102 mounted (e.g., welded) between a pair of lens retainers 104 to form a sub-assembly that is itself mounted (e.g., welded) between a pair of Z-sleeves 106. Each Z-sleeve 106 retains and terminates an optical fiber 108; each lens retainer 104 holds a lens; and device body 102 holds either an isolator or a filter that determines whether optical device 100 functions as an optical isolator or as an optical filter. Optical device 100 has four cavities: one between the end of each optical fiber 108 and the lens in the corresponding Z-sleeve 106 and one between each lens and the isolator/filter in the device body 102. For the fiber optic cable to function properly, optical fibers 108 must be precisely aligned within optical device 100 and the cavities must be completely or at least substantially free of unwanted particles.
Lens retainers 104 and Z-sleeves 106 are typically metal components that are plated to protect them from contamination. For example, lens retainers 104 are typically plated with gold plating over nickel plating, while Z-sleeves 106 are typically nickel plated only. To achieve precise alignment and to prevent contamination from the ambient atmosphere, the plated lens retainers 104 and Z-sleeves 106 are subjected, during fabrication, to a friction process (e.g., lapping) to form a flat (i.e., co-planar) surface.
For example, FIG. 2 shows a side view of a conventional lens retainer 104 for the optical device of FIG. 1. According to the prior art, surfaces 202 and 204, which will be mated (e.g., by welding) to corresponding surfaces on body 102 and Z-sleeve 106 of FIG. 1, respectively, are lappedxe2x80x94after plating, but prior to weldingxe2x80x94to ensure that the mating surfaces are flat. Unfortunately, slivers (e.g., burrs) of the plating may be left on the surface of the lens retainers after lapping, and these slivers may end up as unwanted particles within the cavities of the optical device. Although most of the slivers can be removed manually, vibration test failure rates are typically greater than 9% due to particle contamination. Also, manually removing plating slivers from the lapped surfaces of lens retainers (and Z-sleeves) increases manufacturing time and cost.
The present invention is directed to a technique for reducing the occurrence of plating slivers caused by friction processes (e.g., lapping). The inventors have discovered that plating sliver formation is related to the angle of the plating to the lapping stone or wheel used during the lapping process. To prevent plating slivers from forming, components such as lens retainers and Z-sleeves are chamfered or radiused so that the plating forms an angle to the lapping stone of between about 30 degrees and 60 degrees at the edges of the parts. The present invention can reduce the vibration failure rate to less than about 5%. Also, manual inspection and sliver removal can be eliminated, thereby saving time and labor cost.
In one embodiment, the present invention is a method for reducing occurrence of slivers caused by a friction process during manufacture of a component for an optical device having one or more cavities, comprising the steps of (a) removing one or more edges of a surface of the component to form a non-right angle to the surface; and (b) then using a friction process to remove material from the surface to provide a flat surface, whereby the occurrence of slivers on the component resulting from the friction process is reduced as a result of having removed the one or more edges of the surface, thereby decreasing failure rate for the component due to presence of slivers in the one or more cavities of the optical device.
In other embodiments, the present invention is a component or an optical device comprising a component manufactured in accordance with the above method.
In yet another embodiment, the present invention is a component for an optical device having one or more cavities, the component adapted to be mounted within the optical device at a flat surface of the component, wherein the flat surface of the component comprises one or more removed edges that form a non-right angle to the surface in order to reduce occurrence of slivers on the component resulting from a friction process during manufacture of the component, thereby reducing failure rate for the component due to presence of slivers in the one or more cavities of the optical device.
In still another embodiment, the present invention is an optical device comprising the above component.